Which One of the Following Decisions Most Clearly Reflects a Lack

Which one of the following decisions most clearly reflects a lack of understanding of the concept of sunk costs?

A) You pay to have your car towed back to the repair shop because it was not fixed properly the first time.
B) You decide to get a master's degree because you cannot find a job in the field in which you majored.
C) You decide to purchase a piece of machinery for your business that will eliminate three employees' positions.
D) You study eight hours for a final exam even though there is no way now that you can pass the course.